X Gon’ Give it to Ya: Transmitting FM Radio Over the Air Waves

Who out there misses all of the dog barking, grunting, and terms of endearment toward women provided by our beloved DMX? Something tells me that he is missed on our radio waves. With this brief entry, I will quickly breeze through showing how you can broadcast DMX one more time in your neighborhood (if your country allows for this, of course — this experiment was done at low db…).

I’m still learning how to use GnuRadio Companion (GRC), but I thought it would be of use to share this with the community, those that wish to have a bit of instant gratification with their newly acquired [HackRF, BladeRF, Ettus, etc.] and freshly compiled GRC on their nix VM. Below is a screenshot of my GRC setup along with the GRC file thereafter. The file source (as you can see in the screenshot below) had to be down-sampled at a rate of 16bit in order for GRC to be able to broadcast the audio file. I have it on loop, and the signal to transmit this onto can be adjusted with a slider. This setup is for an Ettus B100. However, with some minor tweaking, this should work on the previously mentioned TX/RX devices.

To modify your audio file, install ‘sox’ along with any libraries needed for whatever file you are handling. If handling an MP3 file, search for libsoxmp3 (or something to that effect). For the file in question, I ran:

sox DMX\ -\ What\'s\ My\ Name.mp3 -b 16 dmx_whats_my_name.wav

That’s it! Now your neighborhood will thank you for rejuvenating a lost art and making it available to everyone, once again.